Kac-Moody groups can be seen as infinite-dimensional generalisations of Chevalley groups. However, our approach will use integration of the adjoint representation of the associated Kac-Moody Lie algebra and a functorial definition due to J. Tits. Unitary forms arise as the fixed point subgroup with respect to a 'twisted' Chevalley involution on the Kac-Moody groups.

We will aim to state and sketch the proof of a classification and rigidity theorem regarding the isomorphisms between two given unitary forms, which is close to a theorem P.E. Caprace proved for Kac-Moody groups.